Method and mining apparatus with movable roof supports



METHOD AND MINING APPARATUS WITH MOVABLE ROOF SUPPORTS Filed July 17, 1951 Aug. 23, 1955 P. v. MALLOY ETAL 9 Sheets-Sheet l INVENTOR5 a: E: Q 5:: v1

8104 V Mnuoy Y flro e ers BY P1901. f/vawy 1955 P. v. MALLOY ETAL 2,716,025

METHOD AND MINING APPARATUS WITH MOVABLE ROOF SUPPORTS Filed July 17, 1951 9 Sheets-Sheet 2 INVENTORS Paw 1 Muaoy BY Pma f/Vnuar aw, I W

Q g t Aug. 23, 1955 P. v. MALLOY ETAL 2,716,025

METHOD AND MINING APPARATUS WITH MOVABLE ROOF SUPPORTS Filed July 17, 1951 9 heets-Sh 3 Aug. 23, 1955 P. v. MALLOY ETAL 2,716,025

METHOD AND MINING APPARATUS WITH MOVABLE RQOF SUPPORTS 9 Sheets-Sheet 4 Filed July 17, 1951 s 3 H mm M i 7 MW & Q a o 3| ma 0 m llml 0 MN Q Q a QQh i 1 1 g- 1955 P. v. MALLOY ETAL.

METHOD AND MINING APPARATUS WITH MOVABLE ROOF SUPPORTS Filed July 17, 1951 9 Sheets-Sheet 5 INVENTORS Pam lfififvaoy By P404 JT M444 or m/B flrrog/vsys uwnnww w IIHIIHHH Aug. 23, 1955 Filed July 17. 1951 P. v. MALLOY EI'AL 2,716,025

METHOD AND MINING APPARATUS WITH MOVABLE ROOF SUPPORTS 9 Sheets-Sheet 6 M Muaoy BY P401. J /mzzoy Aug. 23, 1955 P. v. MALLOY ETAL 2,716,025

METHOD AND MINING APPARATUS WITH MOVABLE ROOF SUPPORTS Filed July 17, 1951 9 Sheets-Sheet 7 Aug. 23, 1955 P. v. MALLOY ETAL METHOD AND MINING APPARATUS WITH MOVABLE ROOF SUPPORTS 9 Sheets-Sheet 8 Filed July 17, 1951 .l M u oy My INVENTORS P904 1 Meaay 824%; Arm/vars P. v. MALLOY ETAL 2,716,025

9 Sheets-Sheet 9 TA ir 8404 K Muay' BY P401. f/V444ay M, v.

Aug. 23, 1955 METHOD AND MINING APPARATUS WITH MOVABLE ROOF SUPPORTS Filed July 17, 1951 United States Patent 0 METHOD AND MINING APPARATUS WITH MOVABLE ROOF SUPPORTS Paul V. Malloy and Paul J. Malloy, Lakewood, Ohio Application July 17, 1951, Serial No. 237,222

31 Claims. (Cl. 262-1) This invention relates to mining and, more particularly, to an improved method and apparatus by which coal or other materials can be mined more safely and in a more rapid, economical and satisfactory manner than has been possible heretofore. The invention is particularly suitable for the mining of coal and is therefore described hereinafter as applied to that use but without any intention of limiting the invention to that material. The method and apparatus of this application is an improvement over the method and apparatus of our copending United States patent application, Serial No. 144,652 filed February 17, 1950, now Patent No. 2,677,- 535 granted May 4, 1954.

As one of its objects this invention provides a novel method and apparatus for mining in which roof-support beams adapted to be progressively advanced with the mining operation are supported on a mine wall being worked, by forming opening means extending into the wall and having a bottom surface sloping forwardly and upwardly toward the mine roof and moving the forward ends of the beams into the opening means in sliding engagement with the sloping bottom surface thereof such that the beams are wedged upwardly toward the mine roof.

Another object is to provide a novel mining method and apparatus of the character mentioned in which the opening means of the mine wall is formed by a forwardly and upwardly sloping longitudinal overcut in the mine wall and which, in some cases, extends into the wall over and beyond the work section to be removed.

A further object is to provide novel mining apparatus in the form of a roof-support comprising an extensible and contractible beam and a power device, preferably a direct acting cylinder device, embodied in the beam and operable to extend and contract the same.

Still another object is to provide novel mining apparatus in the form of a roof-support comprising such a selfpowered extensible and contractible beam and a prop device connected with the rear end of the beam and adapted to be advanced with the beam by a pulling force supplied by the latter.

As another of its objects this invention provides novel mining apparatus of the character mentioned in which the forward beam unit of a self-powered extensible roof beam has holding means thereon and engageable with the mine wall material for preventing backward movement of the forward beam unit during the advance movement of the rear beam unit.

An additional object is to provide novel mining apparatus of this character in which an expansible prop device for supporting the rear end of the self-powered extensible roof beam also forms a holding means for holding the rear beam unit against backward movement during the advance of the forward beam unit.

Yet another object is to provide novel mining apparatus comprising the combination of a roof-support beam adapted to have its forward end supported on a mine wall by engagement in a longitudinal overcut formed in 2,716,025 Patented Aug. 23, 1955 overcut.

It is likewise an object of this invention to provide novel mining apparatus in which a plurality of such selfpowered extensible roof beams form a short-span canopy over a work area which can be readily advanced with the work area as the mining operation progresses and which will permit a safe subsidence of the mine roof immediately behind the work area.

Yet another object is to provide an improved mining machine having a longitudinal rail forming a temporary support for mine roof beams and in which cylinder means connected with the rail operates to elevate or lower the same during the cooperation of rail with the roof beams.

As an additional object, this invention provides an improved mining machine having a boom type cutter adapted to form a longitudinal overcut in a mine wall and in which the cutter is of a longitudinally decreasing thickness toward its outer end such that the cutter will produce a forwardly and upwardly sloping bottom surface in the overcut being formed thereby.

Still another object is to provide an improved mining machine having a boom type cutter adapted to form a longitudinal overcut in a mine wall for receiving the end of roof-support beams and in which the cutter is mounted on an elevator support by which it can be lifted to an operating position and subsequently lowered to an inoperative position to avoid interference with such roofsupport beams.

Other objects and advantages of the invention will be apparent in the following detailed description and in the accompanying sheets of drawings in which:

Fig. l is a plan view showing mining apparatus embodying the present invention and with which the novel mining method can be carried out;

Fig. 2 is a plan view showing a cutting machine and the manner in which it is used in carrying out the present invention;

Fig. 3 is mainly a front elevation of the cutting machine of Fig. 2. and showing the same in use, but also shows one of the novel roof-supports in transverse section;

Fig. 4 is mainly a rear elevation of the cutting machine but also shows the roof beam supporting rail thereof in transverse section and with the forward end of a roof beam supported thereon;

Fig. 5 is a vertical section, taken approximately as indicated by section line 55 of Fig. 1, in which one of the roof-supports is seen in side elevation in its ex tended condition and in which the rear end of the cutting machine is also seen;

Fig. 6 is a top plan view, with portions broken away showing one of the roof-supports in its extended condition;

Fig. 7 is a similar top plan view but showing the same roof-support in its contracted condition;

Fig. 8 is a vertical transverse section taken through one of the roof-supports substantially as indicated by section line 88 of Fig. 7;

Fig. 9 is a plan view similar to that of Fig. l but showing a modification of the mining apparatus and 3 i of Fig. 9 and in which a roof-support of the modified apparatus is seen in elevation in its contracted condition;

Fig. 12 is a top plan view, with portions broken away, further illustrating one of the roof-supports of thermodifled in n p tu :Fig. 13' is a vertical longitudinal section taken through V the. roof-support of Fig. 12 substantially as indicated bysection lines 1313 thereof; 7

' Fig. 14 is a partial vertical longitudinal section taken through the power device of the roof-support of Fig. 12 approximately asindicated by section line 14-14 thereof;

Fig. 15 is a transverse section taken through the roofsupport of Fig. 12' substantially as indicated by the section line. 1515, thereof; e V V FigQf16 is a plan view showing a cutter of one of the roof-supports of the modified mining apparatus in detached relation;

i Fig, 17 is a' partial plan view of the modified cutting machine of Fig. 10;

Fig. I8 is a vertical section similar to that of Fig. 10 but. showing the use of still another form of cutting machine; and

Fig". 19 is a plan view of the cutting machine of Big/18. I e V p In the form of the invention illustrated in Figs. 1 to 8 inclusive .the novel mining apparatus and method are being used to remove coal from an upright mine wall 10' by' applying the mining operation to a work section 11 of adesire'd wall thickness or depth. The mining operation is carried out in a work area 12 adjacent the mine wall 10 and as the coal of the work, section 11 is. removed, this work area shifts back and forth along themine wall and the mining operation is thereby advanced forwardly into the mine Wall, that is, in a general direction extending substantially normal to thelipright wall face. As is understood by those skilled in this art, this system of mining possessesimriottantadvantages overmining operations requiring the formation of numerous individual rooms with supporting pillars of coal remaining between the rooms. p

In accordance with the presentinvention a plurality of mine roof supports 13 form a protective canopy C 7 nected with the rear end of the beam. The roof beams.

have their forward ends supported on the mine wall 10"by engagement in opening means thereof. In accordancewith the present invention this opening means is in-the form 'of a longitudinal overcut 17 formed in the mine wall 10 at a point adjacent the mine roof 19 and by which a supporting ledge 18 is provided having a surface which slopes inwardly and upwardly towards the mine roof as shown in Fig.15.

.The overcut 17- ofthe mine wall 19- compriscs a rear overcut portion 17"extendinglongitudinally along the rear. mine wall portion 10 ahead of the cutting machine 14, that is, along the portionof the mine wall from which material is then being removed The overcut 17 also includes an advanced. overcut l'l formed in the forward mine wall portion 10 in an inwardly or forwardly offset relation to the overcut 17 and extending along and t the rear of the cutting machine 14. V

The roof-supports forming theprotecting canopy C include a number of these supports designated 13 and located in adjacently spacedrelation and which have their forward ends supported on the ledge 13*? of the rear overcut 17 The protective canopy C also includes certain ofthese roof-supports designated 13 at the location of the work area 12 and which have their forward ends supported only by the cutting machine 14 in a manner to be explained hereinafter. All of the roof-supports 131 and 13 are in their contracted condition as shown in Fig. l.

The canopy C also includes extended roof-supports, designated 13, which have their forward ends supported on the ledge 18 provided by the advanced overcut 17 Additionally, the protective canopy includes roof-supports 13 which also have their forward ends supported on the ledge 18 of the forward mine wall portion 10 but which have been contracted to advance the prop devices 16 thereof to a new position in closer relation 7 to the forward wall portion 10 of the mine wall.

In carrying out the mining operation with the system of roof-supports illustrated in Fig. 1, the cutting machine 14 is traveling toward the left and progressively removes coal from the work section 11 during such travel. The cutting machine also operates to form the advanced overc ut 17 to provide the new supporting ledge 18 for-the roof-supports. During this, progressive movement of the work area 12 toward the left, the supporting ledge 18- of the overcut 17 disappears as the coal of the work section 1 1 is removed. The roof beams 13* which thus lose the support of the ledge 18*" are temporarily supportedon thecutting machine 14. V

While the beams 13 are being, temporarily supported on the cutting machine 14 they. are extended tothe condition represented, by the beams 1'3. such that their forward ends will then be supported on the ledge .18 of the new overcut 17 The beams atthe .rear of the cutting machine which have been contracted to. the condition. of the roof-supports.13 leave a portion. of the. mine roof 19 unsupported such that it will cave -in or subsideat the rear of the. contracted roof-supports 13 as. is indicated by the subsided roof material 13*.

This procedure of. progressively removing. thework section 11 of; the rear mine wall portion 18 and then successively extending and. contracting the roof-supports 13 to advance the same atthe rear of the. cutting machine 14, is. carried outas, a continuous operation asthe cutting machine moves along the face of the mine Wall. the cutting machine has reached theend of a desired length of travel. along the mine. wall If it can be reversed to travel-"back in the opposite direction, that is, toward- The roof-supports '13 are more fully disclosed in Figs: 5 to. 24 inclusive and as shown therein eachc-f the roof beams. 15 thereof comprises a rear or main beam unitZt). and a front or auxiliary beam unit 21. The rear beam unit 231 is formed by a pair of laterally spaced structural members such as the I-beams 22' and 23 here shown.

The members 22 and'2'3 are held in substantially parallel relation by a cover plate 24 which extends along the top thereof and issuitably connected therewith and by a rear transverse connecting member 64; The front beam.

unit 20 in which the front beam unit 21 is telescopin'gly' slidable.

The forward endzof the frontbeam'unit 21 is. provided" on the underside thereof with a forwardly and upwardly. sloping bearing surface 29 which is engageable with the sloping surface of the ledge 18 of the overcut17 such that movement of the forward end of the front beamunit into. the opening means of the mine wall ltlwill cause ha p fupp rttqc ds dnp ar y mva d; smine rgof 19; The bearing surface; 29' can be: formed .bypa

When i sloping surface provided on the underside of the front connecting member 27.

The front beam unit 21 is also provided at its forward end with a transverse bar 30 forming a carrier for a laterally extending row of cutters 31. The bar 30 is provided with a dovetail slot 32 in which dovetail projections 33 of the cutters 31 are engageable for connecting these cutters with this bar. The cutters 31 are mounted on the front beam unit 21 so as to locate their cutting edge 34 in or adjacent the plane of the cover plate 24 of the rear beam unit 24) such that when the front beam unit is moved into the overcut 17 this cutting edge will produce a shearing action along the roof 19 by which irregularities will be removed from the upper surface of the overcut to facilitate the movement of the front beam unit into the opening means of the mine wall 10.

As shown in the drawings, a power device 35 is embodied in each of the roof-supports 13 and is here shown as comprising a hydraulic cylinder 36 having a piston 37 reciprocable therein. Thecylinder 36 is located between the members 22 and 23.of the rear beam unit 26 and has its rear end suitably anchored on a transverse pin 38. The pin 38 is rigidly secured to the members 22 and 23 adjacent the rear end of the rear beam unit 29 and has its ends projecting laterally beyond these members. The power device 35 also includes a piston rod 39 connected with the piston 37 and projecting from the forward end of the cylinder. The forward end of the piston rod 39 is suitably connected with the front beam unit 21 adjacent the forward end thereof and, in this instance, is connected with a forked portion of the bearing plate 27 by means of the transverse pin 49.

The cylinder 36 is a double acting cylinder having suitable pressure fluid supply and exhaust connections 41 and 42 adjacent opposite ends thereof such that pressure fluid supplied to the rear. end of the cylinder will actuate the piston 37 toward the right and extend the front beam unit 21 to the position shown in Figs. and 6. When pressure fluid is supplied to the forward end of the cylinder, the piston 37 is moved in the opposite direction causing the front beam unit 21 to be contracted relative to the rear beam unit 20, or when the front beam unit 21 and the piston 37 are held against backward movement in a manner to be presently explained, the pressure fluid supplied to the forward end of the cylinder will cause the cylinder to be moved in a forward direction along the piston rod 39 to thereby advance the rear beam unit by slidably contracting the same along the front beam unit.

An important part of each of the roof-supports 13 comprises a holding means for holding the front beam unit 21 against backward movement, and hence, against withdrawal from its supporting engagement with the ledge 18 of the overcut 17. Such holding means is here shown as comprising a pair of struts 43 connected with the rear end of the front beam unit 21 and disposed in a forwardly inclined upright relation extending between the mine roof 19 and the lower mine wall or floor 44. The struts 43 are here shown as comprising a rigid upper leg member 45 and a lower leg member 46 connected therewith. The lower leg member carries a shoe 47 which is engageable with the mine floor 44 and is provided with an anti-slipping projection 48 adapted to be forced into the material of the mine floor. The lower leg member 46 has its lower end swingably connected with the shoe 47 by a suitable pivot pin 49 and has a threaded upper portion providing an adjustable connection with the upper leg member 45 by which the length of the strut 43 can be adjustably varied.

The struts 43 are connected with the rear end of the front beam unit 21 by being keyed or otherwise secured to the opposite ends of a transverse shaft 59 which extends through and is rockable in a depending portion or lug projection 51 of the rear connecting member 28. The length of the struts 43 is such that these members will assume a forwardly inclined position, as shown in Fig. 5, when the front beam unit 21 is in its extended condition. Any tendency for the front beam unit to move in a backward direction will cause swinging of the struts on the pivot pins 49 which will result in the struts assuming a more nearly vertical position thereby causing the upper ends of the struts to wedgingly engage the mine roof 19. Such wedging engagement of the struts between the mine roof and the mine floor will serve to anchor the front beam unit 21 to the mine wall structure thereby holding this front beam unit against backward movement. The struts 43 also constitute a prop means for supporting the roof beams 15 at an intermediate point thereof.

As already mentioned above, each of the roof-supports 13 includes a prop device 16 at the rear end thereof. As shown in Figs. 5 and 6, this prop device forms a rugged support for the rear end of the rear beam unit 20. The prop device 16 is here shown as comprising a lower section 53 which is supported on the mine floor 44 and an upper section 54 which is shiftable relative to the lower section for causing a substantially vertical expansion or contraction of this prop device. For producing such expansion or contraction the lower and upper sections 53 and 54 have cooperating inclined sliding surfaces 55 and 56 such that movement of the upper section downwardly of the inclined surface 55 of the lower section will cause a contraction of the prop device, and conversely, movement of the upper section in the opposite direction relative to the lower section will cause an expansion of the prop device.

The relative movement between the lower and upper sections 53 and 54 for causing such expansion and contraction of the prop device 16 is produced by a power device embodied in the prop device and which in this instance is a hydraulic cylinder 57. The cylinder 57 has one end thereof pivotally connected with the lower section 53 as by means of the transverse pivot pin 58, and has the outer end of its piston rod 59 pivotally connected with the upper section 54 as by means of a transverse pivot pin 60. The cylinder 57 is a double acting cylinder having suitable pressure fluid supply and exhaust connections 61 and 62 communicating with the ends thereof. Guide plates 63 connected with one of the sections, in this instance the upper section 54, extend in overlapping relation to the lower section 53 for maintaining the sections in properly registering slidable relation.

The roof beam 15 formed by the rear and front beam units 20 and 21 is connected with the prop device 16 in such manner that the rear end of this beam will be supported by the prop device and can be lifted or lowered by the expanding and contracting movement of this prop device. For the purpose of this connection between the roof beam 15 and the prop device 16, the rear beam unit 20 is provided on the underside of its rear connecting member 64 with a convexly rounded transverse pivot shoulder 64 which is rockably engaged in a concavely curved transverse recess 65 provided in the top portion of the upper section 54 of the prop device.

The rear end of the rear beam unit 21 is also connected with the upper section 54 of the prop device 16 by means of a pair of flat links 66 located on opposite sides of the prop device. These links have one end thereof pivotally mounted on the end extensions of the tranverse pin 38 and have their opposite ends pivotally mounted on a transverse pivot pin 67 which is mounted in and extends through the upper section 54. The links 66 retain the convex bearing shoulder 64 of the roof beam 15 rockably engaged in the concave bearing recess 65.

In addition to forming a support for the rear end of the roof beam 15, the prop device 16 also serves as a hold- 1 ing means for holding the rear beam unit 20 against rearward movement during the advance movement of the front beam unit 21 by the power cylinder device 35.

When functioning as such a holding means, the propaligned to receive a lockingpin 74.-

7 Support, the upper section 54 of the prop device 16 is provided with an upstanding portion 68 located to the rear of the rear beam unit 20 and having its top surface located in substantially the same plane as the cover plate 24 of the rear beam unit.

The prop devices 16 are adapted to beadvanced along the mine floor. 44 by -a pulling force applied thereto by 'the self-powered vi-ooflbeamsi 15 with which they are connected as above described. This pulling force is generated by the power cylinder 36 and is transmitted to the prop device 16 through the connection formed by the links 66 and the engagement of the pivot shoulder '64? in the pivot recess fi To assist in. applying this puliin-g force to the propYdevice 16 without causing tippingiof this device or digging OflhBfOI'WfiI'd-filid of itslowersection 53 into the mine floor 44, an additional pulling connection is provided between the forward end-of the-rear bearnunit 20 andthe forward end of the lower section 53. This additional pulling connection is here shown as comprising a flexible cablein the form of a triangular bridle 69 having its two upper ends connected with the side members 22 and 23 of the rear beamfunit 2 as by 7 means of the brackets 69* of the latter and itslower end connected with a bar or link 70 which is, in turn, connected with the forward end of a throughbolt'71 mounted inthe lower section 53. The link 70 is readily detachv, able from the bridle 69 and from the bolt 71 such that this additional pulling means can be removed or swung upwardly out of the way of the cutting machine 14 when not being used to advance the prop device 16. V V

T'ojfacilitate sliding of the prop device 16 on the mine floor 44, the lower section 53 canbe provided with a skid platf72 on thebottom surface thereof. A lockingmeans can also be provided on the prop device 16 for holding,

the sections 53' and 4 in their expanded or contracted condition. This locking means is here shown ascomprising a pair'of platemembers 73 or brackets secured to these sections and having openings adapted to be The construction and operation of the cutting machine 14 and its novel cooperation with the roof-supports13 willbedescribed next. The cutting machine .14 'is here shown as'being 'o'fthe kind which operates to break down the coal of the work section 11 of the rear mine wall por: tion as Well as to form the advanced longitudinal over-.

cut 17' in the front mine wall portion 10 It is not necessary that the cutting machine always be provided withv means for breaking down the work sectionlle, inasmuch as the present invention can be carried out by the use ofaform of cutting machine which does not embody this'means such as the modified forms of cutting machines illustrated in Figs. 17 and 'l9 and described hereinafter. The cutting machine 14 is also shown hereinas being a double-ended machine, that is a cutting machine which The cutting machine14 comprises a suitable frame a structure 75 supported on "tread member 76 of the endless'belt type. The. cuttingrnachine 14 is a self-powered machine having'one'or'more' electric motors 77 mounted thereon for driving the treads 76 to propel the machine in the'desire'd direction. At its left end as seen in Figs.

2 and 3','thecuttin g'machine '14 is provided with a rotat ableeutter-or bit-device 78 having 'a centra'l drill portion" '79 -and' laterally spaced bit elements 80 811(181; a V Y The cutter 78-is drivemfrom one end of a double ended electricmotoig .82through. meshing gearand-pinion 8" members 83 and '84. The driving connection between the motor 82 and the cutter 78 includes a suitable clutch device by which the cutter can be disconnected from the motor and which, in this instance, is formed by having the pinion .84 slidably splined on the motor shaft 85 for movement into and out of meshing engagement with the gear 83.

At its left end the cutting machine 14 is also provided I with a transversely extending rotatable screw conveyor 86 and a transversely extending curved deflector plate or plow 87 adjacent this conveyor. During the operating travel of the cutting machine 14 toward the left, the'coal which is loosened from the work section 11 of the mine' wall by the cutter 78, is deflected against the conveyor; 86 by the plow 87. Rotation of the conveyor 86 feeds the coal in a rearward direction onto a suitable delivery conveyor '88 by which the coal is supplied to a main conveyor or other suitable carrying means (not shown) for removal from the mine. The conveyor 86 is driven by an electric motor '89--through a clutch device 90,- a

shaft 91 and suitable gearing 92 At the left endthereof, the cutting machine 14 is also provided with a boom-type cutter 'orcutting boom 93 which is shown in Figs. 1, 2 and 4 in its operative position for forming'thev advanced overcut 17 in the front mine wall portion 10 The boom-cutter 93 comprises a boom structure 93 and a pair of upper and lower chainbelt cutters. 94 and 95 carrying projecting cutting teeth 96. At its right end the cutting machine 14 is provided with another such boomcutter 97 to which further reference will presently be made.

The upper. and lower chain belt cutters 94 and 95 extend around and are driven by suitable sprockets mounted on a substantially vertical shaft 98. The upper chain belt cutter 94 lies in ,a substantially horizontal plane such that it will form the upper surface .of the overcut 17 in a location which will lie in substantially the same plane as the. surface of the mine roof 1 9. Thelow'er chain belt cutter95' has the rear end 9.5 thereof disposed in a horizontal plane and the front end 95 thereof in a plane which extends forwardly and upwardly at the same angle as the upwardly and forwardly sloping surface desired for the ledge 18. By reason of the in clined relation thus provided'by the front ends of the chain belts 94 and 95, the cutting boom 93 will have .a tapered shape and thickness corresponding with the tapered shape and size desired for the overcut 17.

The boom cutter 93 and its vertical drive shaft 98 are mounted on an elevating table 99 by which this cutter can be raised to the elevation at which the overcut ,17 is to be formed and when the cutter is not in use it can be lowered to an elevationwhich will enable .itto pass beneath the roof-supports 13, that is, to the elevation in which the boom cutter 97 is shown, in Figs. 1, 2 and 4. t

The shaft 98 carrying the driving sprockets for the chain belts 94 and 95 is driven by an electric motor 100 through suitable gearing 101. The table 99 ,is lifted and lowered by the action of suitable hydraulic cylinders 102' and is guided during such movements by one or more upright guide posts 103 When the boom cutter 93 is in its operating position, it projects forwardly from the cutting machine 14 at substantially right angles to the longitudinal axis of this machine, as shown in Figs. 1 and 2, and the chain belt cutters 94 and 95 perform 'a'cutting operation on the mine wall; 10 during the longitudinal movement of the cutting machine toward the left as seen in Fig. 2. The cutting boom 93 is swingable about the axis of the shaft 98to and from its. operative position, but such'swinging is prevented while the boom is in its operating position by arigid thrust link 104. This thrust link has one end thereof connectedwith'the. boom structure 93* and itsother end. suitably anchored on the frame of thecutting.

machine. e

I As-mentionedabove,- the cutting. machine. 14; iisa.

double-ended machine and is accordingly provided at the right end thereof with a rotary cutter 105 which is substantially identical with the rotary cutter 78 and is driven from the main motor 82 in the same manner. The right end of the cutting machine is also provided with a transversely extending conveyor 106 and adjacent curved plate or plow 107 which are similar to the conveyor and plow 36 and 87 of the opposite end. A delivery conveyor 1118 similar to the delivery conveyor 88 is also provided adjacent the rear end of the conveyor 106. The conveyor 106 is adapted to be driven by the motor 89 through the clutch 90 and through suitable gearing 109 which is connected with the clutch 90 by the shaft 110.

The second cutting boom 97 with which the cutting machine 14 is provided, as mentioned above, is substantially identical with the cutting boom 93 and is mounted on an elevating table 112 and adapted to be driven by an electric motor 113 in the same manner as the cutting boom 93. The cutting boom 97 is shown in Figs. 1, 2, 4 and in its retracted or inoperative position in which it has been swung about the axis of the shaft 98 and in a rearward direction away from the mine wall portion In this inoperative position the cutting boom 97 has also been moved downwardly by lowering of he table 112 to the elevation shown in Figs. 4 and 5 in which this cutting boom will pass beneath the roof-supports 13.

The cutting boom 97 is held in this rearwardly swung position by a rigid holding link 114 having one end thereof connected with the boom structure 97 and its other end suitably anchored on the frame of the cutting machine. A pair of the holding links 104 and 114 is provided for each of the cutting booms 93 and 97. When the holding link 104 is not in use it occupies a parked position 1'94 on the frame of the cutting machine and likewise when the link 114 is not in use it occupies a parked position 114 As another important feature thereof, the cutting machine 14 is provided with an elongated longitudinally extending supporting rail 115 forming a temporary support for the forward ends of the roof-supports 13 The rail 115 may comprise a structural member such as an I-beam and is carried by piston rods 116 and 117 extending upwardly from a pair of hydraulic cylinders 118 and 119 which are suitably mounted on the frame of the cutting machine.

The hydraulic cylinders 118 and 119 provide for a lifting or lowering of the rail as may be desirable for locating the upper edge thereof substantially in the plane of the lower edges of the roof-supports 13. By actuation of these hydraulic cylinders, the rail 115 can be elevated to cause the same to lift the roof-supports 19 and assume the roof load thereof or to align these roofsupports with respect to the advanced overcut 17 such that the front beam units 21 of these roof-supports will engage properly in the overcut when the beams are extended to the condition of the roof-supports 13. The rail 115 is moved in an endwise direction by the cutting machine 14 so as to engage under successive roof-supports 13 as the mining operation progresses along the mine wait 19. The removal of the work section 11 by the cutting machine causes the rear overcut 17 to be progressively destroyed and at the location where this overcut has been thus destroyed, the roof-supports 13 and the roof load thereof will be carried by the rail 115. 7

As here shown, the cutting machine 14 may also be provided with a pump 121 driven by an electric motor 122 and which generates hydraulic pressure for various purposes such as the operation of the hydraulic cylinders 102 which actuate the tables 99 and 112 which support the cutting booms 93 and 97, and the cylinders 118 and 119 which actuate the rail 115.

From Figs. 1 to 8 inclusive of the accompanying drawings and from the foregoing detailed description, it will now be readily understood that this invention provides novel mining apparatus which includes self-powered roofsupports adapted to form a short-span protective canopy over a work area adjacent a mine wall being worked. It will also be recognized that the roof-supports herein provided never need to be withdrawn from the mine wall opening means and that the only movement which is imparted to the roof-supports is an advance movement in the general direction in which the mining operation is being advanced. It will now likewise be understood that this invention also provides a novel cutting machine adapted to cooperate with such roof-supports in a manner to provide a temporary support for certain of the roof-supports and also has cutting means operable to form opening means in the mine wall at an advanced point to receive the forward ends of the roof-supports which are being advanced with the mining operation. With respect to the prop device at the rear end of the roof beam, it will be seen that this prop device constitutes a main prop which is located relatively close to the work area and is sufficiently strong and rugged to safely support the roof against cave-in, even though the forward end of the roof beam may be temporarily slacked away from the mine roof either by destruction of the supporting ledge of the coal wall or by lowering of the supporting rail of the cutting machine.

Figs. 9 to 17 inclusive show mining apparatus generally similar to that already described above but which rep resents a modification thereof. In the modified mining apparatus and method a roof-support 125 of a somewhat different form and a cutting machine 126 of a more simplified construction are used. in the mining operation as carried out with the modified apparatus and method, the supporting ledge 127 of the longitudinal overcut 128 formed in the mine wall 129 is always maintained and the forward ends of the roof-supports 125 are continuously engaged in the opening means formed by the longitudinal overcut.

In Fig. 9 of the drawings, the roof-supports 125 are shown in their contracted condition and extending over and beyond the work section 130 which is to be removed from the mine wall. The overcut 123 at this point of the mine wall is of a depth great enough to extend over and beyond the thickness of the work section 130 which is to be removed. As shown in Figs. 9, 11 and 13 the forward ends of the roof-supports 125 are supported on that portion of the ledge 127 which lies beyond or forwardly of the work section 130. The roof-supports 125 are shown in Fig. 9 as also being in their contracted condition and as having their forward ends supported on that portion of the ledge 12? which has remained as an intact portion of the mine wall 129 after the work section 131) has been removed therefrom. The roof-supports 125 and 125' thus form a short-span protective canopy D over the work area 131 serving the work section 130.

Fig. 9 of the drawings also shows the opening means of the mine wall 129 as having been deepened by the cutting machine 126 to form an advanced overcut 123 and an advanced supporting ledge 127 A roof-support 125 is shown in its extended condition in which the forward end thereof is engaged in the advanced overcut 12? and is now supported by the advanced ledge 127 The roof-supports located rearwardly of the support us and here represented by the roof-support 125 are in their contracted condition in which they have been advanced for the mining operation to be performed on the advanced work section 136 These contracted roof-supports 125 also have their forward ends supported on the advanced ledge 127 and form a protective canopy over the advanced work area 132. As the roof-supports are advanced to the position of the roof-supports 125 the roof material is permitted to cave in at the rear of these supports as indicated by the subsided roof material 133.

The roof-supports 125 are generally similar to the roof-supports 13 aiready described above in that they each comprise an extensible self-powered roof beam 135 and 11 apropdevice 136. ,As shown in Figs. 12, 13 and 15,

eachiof the roof beams comprises a rear beam unit 137 and a forward beam unit 138. The rear beam unit 137 comprises a pair of laterally spaced'structural members such as the I-beams 139 and 140 which are connected in parallel relation by the cover plate 141 and the rear connecting member 142. The adjacent channel recess of the l-beams 139 and 140 define 'a guideway in which the front beam unit 138 is slidable. The front beamunit 13S also comprises a pair of spaced structural memberssuch as the I-beams 143 and 144 which are connected in parallel relation by front and rear transverse connections 145 and 146.

For'causingrelative longitudinal movement between the rear and front beam units 137 and 138, the roof beam 135 is provided. with a power device preferably in the form of a hydraulic cylinder 147. The cylinder 147 'is here shown as being rigidly connected with the front beam unit 138 as by being welded into and form ing a part of the front and rear transverse connections 145aud 146'. A piston 148 slidable in the cylinder 147 is connected with a piston rod 149 which projects from the rear end of the cylinder and is anchored on the connecting member 142 of the rear beam unit 137. The piston rod 149 is a hollow member and, as shown in Fig. 14, forms a connecting passage which communicates with the chamber of the cylinder 147 which is located at the rear of the piston 148. A tube 150 extending through the piston rod 149 and the piston 148, provides'a connecting passage for the chamber of the cylinder which is located in front of the piston.

At its forward end, the front beam unit 138 is provided with hearing plates 151 mounted on the lower flanges of the side members 139 and 140 and each having a forwardly and upwardly inclined lower bearing surface 151 which is slidable on the forwardly and upwardly inclined ledge 12-7 of the overcut 128. Movement of the front beam unit 133 into the overcut 128 with the bearing surfaces 151 in sliding engagement with the ledge 127 causes the beam 135 to he forced upwardly toward the mine roof 152.

'The roof beam 135 is also provided with holding means for preventing withdrawal of the front beam unit 138 from the overcut 128. This holding means is here shown as comprising a pointed plunger or stem 153 adapted to bc'forced against or into the material of the mine roof 152 The stem153 is connected with and actuated by the piston 154 of a hydraulic cylinder 155 which is suitably mounted'on the forward end of the front beam unit 138. Pressure fluid is adapted to be supplied to the cylinder 155 through an extensible conduit formed by telescoping pipe members 156 and 157 which gave the front beam unit 138'as by being provided with hook portions 158 and 1'59 engageable in recesses of'the'. forward end of this beam unit and also having rear: wardly extending stem portions 158 and 159 which are 'slidable'fin the outer channel recesses of the rear beam unit and are retained therein by the upturned end portions of the transverse retaining bar 160. The cutters 158 and 159 are of such, shape and are so located on the front beam unit 138 that they define a serrated cutting edge 161 which will lie substantially in the plane of-thc mine roof 152 and will perform a desired cutting action-on the mine wall material during forward movement of the front beam unit.

The prop device 136 is formed by relatively movable lower and upper sections 162 and 163 simlar to the prop device 16 described above, and serves the same purpose in'supportig th'e rearend of the roof beam 135 andin forming' ja holding means for'the rear beam unit '137'as well as a means for controlling the subsidence of the roof material of the mine roof 152. The prop device 136 includes a powerdevice, preferably a hydraulic cylinder 164, which produces relative movement between the lower and upper sections 162 and 163 in the same manner and for the same purpose as has been described above for the prop device 16.

The rear beam unit 137 is connected with the prop device 136 by the rockable engagement of a transverse convex bearing portion 142'"- of the rear beam unit in a concave bearing recess 1660f the upper section 163. The convex bearing portion 142 is formed by a depending portion of the rear connecting member 142..

The rear beam unit is also connected with'the' prop device 136 by means ofpivoted links 167 similar to the links 166 and by .a pair of tension springs 168 which have" their upper ends connected with pins 169 projected from the rear beam unit 137 and have their lower ends connected with pins 170 projecting from the lower section 162 of the prop device.

The cutting machine 126is further illustrated in Figs. 10 and 17 and comprises, in general, a frame172 supported by treads 173 and 174015 the endless belt type and extending in spanning relation to a conveyor 175 by which the coal removed from the work section is carried from the Work area.- The cutting machine 126 also includes a pair of boom-type cutters 176 and 177 extending in forwardly and upwardly inclined relationand comprising boomstructures 176 and 177 each having the booms can be varied in accordance with the loca- 'tion and inclination desired .for the cut 183 which is formed in the mine wall by these cutting booms.

The cutting machine 126 also includes a longitudinal supporting rail 184 which is mounted on the frame 172 by being connected with the movable members 185 of a pair of hydraulic cylinders 186.. The rail ,184 forms a temporary support for the beams 135 of the roofsupports 125 and 125 during'the passage of the cutting machine beneath these beams, The rail 184 is used in particular to support the beam 135 of the roofsupport 125. and the roof load thereof while the front beam unit 138 of this roof-support is being extended into the advanced .overcut 128*".

7 By supplying pressure fluid to one or b oth of the hydraulic cylinders 186, the rail 184 can be moved upwardly to lift the beam 135 of the roof-support,125 while the front beam unit 138 of this roof-support is being thus extended into the advanced ,overcut 128.

By providing the cutting machine 126 with the two cutting booms 176 and 177, this machine will be doubleended such that it can be used to form the advanced overcut 128* during movement of the cutting machine in either direction along the mine wall. In using this cutting machine the cutting boom which is in the operative position,

such as the cutting boom 176 during movement of the cut ting machine toward the left as seen in Figs. 9 and 17, will form the forwardly and upwardly inclined cut 183 in the mine wall. As shown in Fig. 10, the cut 183 extendsinto' the mine wall at an elevation below the previously formed overcut 128 and the cutting booms are of a length such viously formed overcut 128 by only a relatively thin wall of coal 187, this remaining coal wall will usually be broken away simultaneously with the forming of the cut 183. The breaking away of the intervening wall 187 destroys the ledge 127 on which the roof-supports 125 were previously carried, but since the rail 184 of the cutting machine has already moved into position beneath these roof-supports they will be supported thereby.

After the inclined cut 183 has been formed by the cutting boom 176 and the intervening coal wall 187 has broken away, there will still remain a triangular strip or block of coal 188 above the inclined cut and forwardly of the overcut 128 as shown in Fig. 10. This triangular strip or block of coal 188 remains connected with the mine roof 152 and is separated from the mine roof by the cutting edge 161 of the front beam unit 138 when the latter is advanced relative to the rear beam unit by the hydraulic cylinder 147. Depending upon the characteristics of the coal comprising the strip 188, this strip may be separated from the mine roof by a single forward movement of the front beam unit 138 or its separation from the mine roof may require repeated forward movements of the front beam unit during which this beam unit and the cutting edge 161 thereof function as a reciprocating drill. After the strip of coal 188 has been thus removed, the front beam unit 138 will occupy the extended position engaging in the advanced overcut 128 as represented by the front beam unit of the roof-support 125 shown in Fig. 9.

When the front beam unit 138 of the roof-support 125 has been thus actuated to deepen or enlarge the overcut 128 and occupies the extended position shown in Fig. 9, the hydraulic cylinder 155 is then actuated to extend the stem 153 to engage in the material of the mine roof 152. Such engagement of the stem 153 with the mine roof will anchor the front beam unit 138 on the mine wall structure and will hold this beam unit against backward movement. While the front beam unit is thus being held against backward movement, pressure fluid supplied to the hydraulic cylinder 147 will cause a forward movement of the piston 148 to thereby advance the rear beam unit 137 along the front beam unit and at the same time pull the prop device 136 along the mine floor to the advanced position of the prop device of the roof-support 125 During this advance movement of the prop device 136, the roof material is left unsupported and subsides at the rear of the prop device as indicated at 133 in Fig. 9.

Figs. 18 and 19 show a cutting machine 190 which is generally similar to the cutting machine 126 but is provided with an additional cutting boom 191 which is in such location that it will remove the above described strip or block of coal 188 to thereby complete the advanced overcut 128 without requiring the removal of this remaining coal by the cutting edge 161 of the front beam unit 138. In other respects the cutting machine 199 is substantially identical with the cutting machine 126 and the same reference characters have therefore been used to designate the same corresponding parts.

The additional horizontal cutting boom 191 is located between the inclined cutting booms 176 and 177 and is driven from an individual electric motor 192 through a suitable flexible shaft 193 and suitable gearing 194. When a cutting machine 190 embodying the additional horizontal cutting boom 191 is used, the cutting blades 158 and 159 can be omitted from the front beam units of the roofsupports 125 but preferably these cutters are still provided on the front beam units for the purpose of clearing away from the mine roof any projections or irregularities remaining thereon after the passage of the cutting machine. Likewise in the case of the cutting machine 14 which forms the advanced overcut 17 the cutters 31 could be omitted from the front beam units 22 of the roof-supports 13 but are preferably still provided on these beam units for the purpose of clearing away any irregugitudinal movement 14 larities or projections which may remain on the mine roof 19 after the passage of the cutting machine.

The cutting boom 191 includes a forwardly and upwardly inclined hollow boom structure 191* which supports the cutting head carrying the chain-type cutter and also forms a conduit for the flexible shaft 193. The boom structure 191 is supported and actuated by the movable members of a pair of hydraulic cylinders 195 and 196.

From the illustration contained in Figs. 9 to 19 inclusive and from the foregoing detailed description relating thereto, it will now be readily understood that this invention provides improved mining apparatus and a novel method of mining by which a work section can be removed from a mine wall by a progressive advance movement during which roof-supports form a protective canopy over the work area and are advanced with the mining operation while the forward ends of the roof beams remain continuously engaged in an opening means or longitudinal overcut of the mine wall.

in general, with respect to the mining apparatus and method herein disclosed in Figs. 1 to 18 inclusive, it will now be recognized that this invention provides many important advantages and makes possible the rapid and safe removal of coal from a mine wall without need for establishing individual mine rooms with intervening pillars for supporting the mine roof. The apparatus of the present invention is relatively simple since it consists largely of self-powered roof-supports which are in continuous use and are advanced progressively with the advance movement of the mining operation. Additionally, it will be seen that the present apparatus permits the mining operation to be carried out with the cutting machine in substantially continuous service and without involving the delays and idle periods which occur in mine operations where cutting machines are required to be advanced into and backed out of individual mine rooms. Likewise, it will be seen that in forming the protective canopy for the work area, the self-powered roof-supports also provide a clear and direct passage for efficient ventilation of the work area and permit a safe subsidence of the roof material at substantially the rate that the mining operation is advanced into and along the coal wall with the result that only a minimum number of roof-supports need be provided and maintained in service.

Although the improved mining apparatus and novel method have been illustrated and described herein to a detailed extent, it will be understood of course, that the invention is not to be regarded as being limited correspondingly in scope but includes all changes and modifications coming within the spirit of the invention and the terms of the claims hereof.

Having thus described our invention, we claim:

1. A mine roof support comprising, a beam having one end thereof adapted to be supported on a mine wall by engagement of said one end in preformed opening means of said wall, said beam comprising elongated substantially longitudinally aligned front and rear beam units, connecting means connecting said beam units in such substantially longitudinally ali ned relation and for relative lontherebetween, said front beam unit being extensible relative to the rear beam unit by said relative longitudinal movement for advancing said one end of the beam in said opening means while said rear beam unit remains relatively stationary, and thrust producing actuating means embodied in said beam and having operative connection with said rear and front beam units for causing such extension of the latter unit.

2. A mine roof support comprising, a beam having one end thereof adapted to be supported on a mine wall by engagement of said one end in preformed opening means of said wall, said beam comprising elongated substantially longitudinally aligned front and rear beam units connected with each other for relative longitudinal movement therebetween such that said front beam unit is extensible relative to the rear beam unit for advancing said one end of the beam insaid opening means andrsaid and actuating means comprising relatively movable parts connected with said front and rear beam units respectively and being operable to cause the extensible and. contractible movements of said units in succession.

3. In mining apparatus, a roof support beam having one end thereof adapted to be supported on a mine wall rear beam unit is contractible relative to the front beam unit,

by engagement of said one end in opening means of said 7 of said auxiliary beam unit in said opening means, and a power device embodied insaid beam and comprislng relativelymovable parts having operative connection respectively with said main and auxiliary beam units and being effective to extend the latter'unit by said relative sliding movement. a

4. In mining apparatus, a roof support beam having one end thereof adapted to be supported on a mine wall by engagement of said one end in opening means of said wall, said beam comprising elongated substantially longitudinally aligned main and auxiliary beam units having their adjacent end portions connected with each other for relative longitudinal sliding movement therebetween, the auxiliary beam unit being extensible relative to said main beam unit by said sliding movement for engagement of said auxiliary beam unit in said opening means and said main beam unit being contractible relative to said auxiliary beam unit while the latter is stationary, and a power cylinder device embodied in said beam and comprising cooperating direct acting piston and cylinder members connected with said main and auxiliary beam units and eifct-ive to cause said relative movement for extending the latter beam unit and subsequently contracting the main beam unit. 7 a p 5, In'mining apparatus,'a roof support beam having one;end thereof adapted to be supported on a mine wall by engagementof said one end in opening means of said wall, said beam comprising elongated substantially longitudinally aligned main and auxiliary beam units having their adjacent end portions connected with each other for relative longitudinal sliding movement therebetween, the auxiliary beam unit being extensible relative to said main :beam unit by said'sliding movement for engagement of said auxiliary'beam unit in said opening means, power means embodied in said beam and comprising relatively movable parts connected with said main and auxiliary beam un ts respectively and being operable, to extend the latter unit by said relative sliding movement and to subsequently contract said main beam unit, and holding means on said auxiliary beam unit and adapted for holding engagement with the mine wall material for anchoring said auxiliary beam unit thereon while said main beam unit is being contracted.

6.}In mining apparatus, an extensible and contractible mine roof support .beam comprising substantially aligned main and auxiliary beam units having their adjacent end portions connected with'each other for relative longitudinal telescoping movement therebetween, said auxiliary beam unit .having its forward end engageable in opening means of a mine wall for supporting the forward end of said beam thereon, strut means swingably connected with said auxiliary beam unit and engageable in a downwardly and rearwardly inclined wedging relation with the mine floor for releasably holding said auxiliary beam unit 7 against backward movement, and actuating means embodied said beam and comprising relatively movable partsconnected with the respective beam units for causing said,relaitve longitudinal movement therebetween, said contractible by such relative movement between said a 16 V by advancing said auxiliary beam unit for engaging the forward end thereof in said opening meanstand to'then shorten said beam by advancing said mainbeam unit along said auxiliary beam unit toward said mine wall..

7. In mining apparatus, a roof support beam having one end thereof adapted to be supported on a mine wall by engagement in opening meansof said wall having an inwardly and upwardly sloping bottom surface, said beam comprising elongated substantially aligned main and auxiliary beam units having their adjacent end portions connected with each other for relative longitudinal movement therebetween, said auxiliary beam'unit being extensible relative to said main beam unit by said relative longitudinal movement for advancing said auxiliary beam unit into said opening means, and forwardly and upwardly sloping bearing means on said auxiliary beam unit and adapted to slide on said slopingbottom surface for wedging said beam upwardly toward the mine roof in response to the advance movement of said auxiliary beam unit into said opening means. 7

8. In mining apparatus, a roof support beam having one end thereof adapted to be supported on a mine wall by engagement in opening means of the wall having an inwardly and upwardly sloping bottom surface, said beam comprising elongated substantially aligned main and auxiliary beam units having their adjacent end portions connected with each other for relative longitudinal movement therebetween, said auxiliary beam unit being extensible relative to said main beam unitby said relative longitudinal movement for advancing said auxiliary beam unit into said opening means, forwardly and upwardly sloping bearing means on said auxiliary beam unit and adapted to slide on said sloping bottom surface for wedging said beam upwardly in response to the advance movement of said auxiliary beam unit into said opening means, and actuating means embodied .in .said beam and comprising relatively movable parts having operative connection respectively with said main and auxiliary beam units and effective to cause said relative longitudinal movement between said beam units.

9.'In mining apparatus, a roof support comprising a beam having a forward end adapted to be supported on amine wall by engagement in opening means thereof, a. prop device supporting the rear end of said beam, and

' connecting means connecting said'prop device with said beam including pulling force transmitting means effeclongitudinally aligned main and auxiliary beam units connected with each other for relative longitudinal movement vtherebetween and an actuating means having relatively movable parts connected with the respective beam units andtoperative to cause .said relative longitudinal movement, said prop device comprising relatively movable cooperating members and being expansible and members for lifting or lowering the rear endof said' beam and for holding sai'd'rear end engaged against the i v mine roof, said a'ctuating'means being effective to extend said auxiliary beam-unit relative to said main beam unit while'said prop-device is expanded for advancing said auxiliary beam unit into said opening means and also being effective to advance said main beam unit'and said.

prop device while the latter is contracted by causing advance movementof said main beam unit'relative to said auxiliary beam runitn v 10. In mining. apparatus, .aroof beam 'having a forward end adapted to be' supported on a, minewall. by engagement in opening means extending into said wall adjacent the mine roof, said;beam comprising elongated main and auxiliary beam units connected; with each other forrelative longitudinal movement therebetween, actuating means embodied in said beam and. comprising relativ'ely movable parts connected with the respective beam actuating means being'effe'ctive to first lengthen said beam 75 units, said actuating means being operable to impart endwise movement to said auxiliary beam unit for advancing the same into said opening means and to subsequently advance said main beam unit toward said wall and along said auxiliary beam unit While the latter is engaged in said opening means, a prop device supporting the rear end of said beam above the mine floor and comprising cooperating relatively movable Wedge members, said prop device being contractible and expansible by such relative movement between said Wedge members for lowering said rear end and for lifting and engaging said rear end against the mine roof, and means connecting said main beam unit with said prop device including pulling force transmitting means for applying a pulling force to the latter for moving the prop device along the mine floor during the advance movement of said main beam unit.

11. In mining apparatus, a roof beam having a forward end adapted to be supported on a mine wall by engagement in opening means extending into said wall adjacent the mine roof, said beam comprising elongated main and auxiliary beam units having their adjacent ends connected with each other for relative longitudinal sliding movement therebetween, actuating means embodied in said beam and comprising relatively movable parts connected with the respective beam units, said actuating means being operable to impart endwise movement to said auxiliary beam unit for advancing the same into said opening means and to subsequently advance said main beam unit toward said wall and along said auxiliary beam unit while the latter is engaged in said opening means, holding means connected with said auxiliary beam unit and engageable with mine wall structure for retaining said auxiliary beam unit in said opening means and holding the same against backward movement during the advance movement of said main beam unit by said actuating means, a prop device supporting the rear end of said beam above the mine floor, said prop device comprising cooperating relatively movable members and being contractible and expansible by such relative movement between said members for lowering said rear end and for lifting said rear end to press said main beam unit against the mine roof for holding said main beam unit against backward movement, and means connecting said main beam unit with said prop device including pulling force transmitting means for applying a pulling force to the latter for moving the prop device along the mine floor during the advance movement of said main beam unit.

12. In mining apparatus, a roof beam having a forward end adapted to be supported on a mine wall by engagement in opening means extending into said wall adjacent the mine roof with the bottom of said opening means sloping inwardly and upwardly toward said roof, said beam comprising elongated main and auxiliary beam units having their adjacent ends connected for relative longitudinal sliding movement therebetween, actuating means mounted on said beam and comprising relatively movable parts having operative connection with said auxiliary and main beam units respectively for advancing said beam units in succession, bearing means on said auxiliary beam unit and movable on the sloping bottom of said opening means for wedging said beam upwardly toward said roof in response to advance movement of said auxiliary beam unit in said opening means by said actuating means, holding means connected with said auxiliary beam unit and engageable with mine wall structure for preventing backward movement of said auxiliary beam unit and withdrawal thereof from said opening means during the advance movement of said main beam unit by said actuating means, a prop device supporting the rear end of said beam above the mine floor, said prop device comprising cooperating relatively movable members and being contractible and expansible by such relative movement between said members for lowering said rear end and for lifting said rear end to press said main beam unit against the mine roof for holding said 13. Mining apparatus as defined in claim 12, in which the connecting means between said beam and prop device also includes pivot means providing for swinging of said beam relative to said prop device.

14. In mining apparatus, a roof beam having a forward end adapted to be supported on a mine wall by engagement in opening means extending into said wall adjacent the mine roof, said beam comprising elongated main and auxiliary beam Units having their adjacent ends connected for relative longitudinal sliding movement therebetween, actuating means mounted on said beam and comprising relatively movable parts having operative connection respectively with said auxiliary and main beam units for advancing said beam units in succession and engaging said auxiliary beam unit in said opening means, holding means connected with said auxiliary beam unit and engageable with mine wall structure for preventing Withdrawal of said auxiliary beam unit from said opening means during the advance movement of said main beam unit by said actuating means, a prop device supporting the rear end of said beam above the mine floor, and means connecting said main beam unit with said prop device including pulling force transmitting means for applying a pulling force to the latter for moving the prop device along the mine floor during the advance movement of said main beam unit, said prop device being expansible and contractible for lifting and lowering said beam relative to said roof and for holding said rear end engaged with said roof, said prop device comprising relatively movable prop members having cooperating wedging surfaces and actuating means connected with and operable to cause relative movement between said prop members.

15. In mining apparatus, a mine roof support beam adapted to be supported on a mine wall by endwise engagement in opening means extending into said wall adjacent the mine roof, said beam comprising elongated substantially longitudinally aligned telescoping beam units one of which is extensible and retractible by reciprocating movement relative to the other and has its forward end engageable in said opening means, actuating means embodied in said beam and including a reciprocably movable part operably connected with said one beam unit and effective on the latter to produce said reciprocating movement thereof, and cutter means on the forward end of said one beam unit and actuated by the reciprocating movement thereof for enlarging said opening means in said mine wall.

16. In mining apparatus, a plurality of roof beams having their forward ends supported by a longitudinal overcut formed in a mine wall adjacent the mine roof, a cutting machine movable along said wall beneath said beams and having a cutting boom adapted to form a second longitudinal overcut in said wall to constitute a new support for said forward ends when said beams are advanced to a new position, and a rail mounted on and connected with said cutting machine and forming a support movable with said cutting machine and engaging certain of said beams from the underside thereof for supporting the forward ends of said certain beams when the first-mentioned overcut is destroyed by the removal of material from said wall.

17. In mining apparatus, a plurality of roof beams having their forward ends supported by a longitudinal overcut formed in a mine wall adjacent the mine roof, a cutting machine movable along said wall beneath said beams and having a cutting boom adapted to form a second longitudinal overcut in said wall to constitute a new support for said forward ends when said beams are supporting the forward ends of said certain beams when the first-mentioned overcut is destroyed by the removal of material from said wall, said beams comprising connected' main and auxiliary beam units and being extens ble by forward relative movement of said auxiliary beam units for engagement of the forward ends of said certain with said second overcut while said certain beams are being supported by said rail.

18, In mining apparatus, a cutting machine movable 7 along a mine wall and having a cutting boom adapted to form a longitudinal overcut in said wall adjacent the mine roof, a support rail mounted on and connected with said cutting machine, a roof beam comprising elon- "gated substantially longitudinally aligned main and auxiliary beam units having their adjacent ends connected with each other for relative sliding movement therebetween, prop means connected with and supporting the rear end of said main beam unit and being adapted to move the same into engagement with said roof, said main beam unit extending forwardly from said prop means and over said support rail transversely thereof and being supported at its forward end and in a position ad acent said roof by said support rail, said auxiliary beam unit being extensible relative to said main beam unit for engagement of said auxiliary beam unit in said overcut, and actuating means mounted on said roof beam and 7 comprising relatively movable parts having operative connection respectively with said main beam unit and said auxiliary beam unitfor extending the latter.

19. In mining apparatus, a cutting machine movable along a mine wall and having a cutting boom adapted to form a longitudinal overcut in said .wall adjacent the mine roof, a support rail mounted onand connected with said cutting machine, a roof beam comprising elongated substantially longitudinally aligned main and auxiliary beam units having their adjacent ends connected with each other for relative sliding movement therebetween, a prop device Supporting the rear end of said main beam unit, said prop device comprising cooperating relatively movable members and being expansible and contractible by such relative movement between said members for lifting and lowering said main beam unit and for holding said main beam unit engaged against the mine roof, said main beam unit extending forwardly from said prop device over said support rail transversely thereof and being supported atits forward end and in a position adjacent said roof by said support rail, said auxiliary beam unit being extensible relative to said main beam unit for engagement of said auxiliary beam unit in said overcut, actuating means mounted on said roof beam and comprising relatively movable parts, having operative connection respectively with said main and auxiliary beam units for extending said auxiliary beam unit and subsequently advancing said main beam unit, holding means connected with said auxiliary beam unit and engageable with mine wall structure for preventing backward movement of said auxiliary beam unit during the advance movement of'said main beam unit, and means connecting said prop device with said beam unit for advance movement by the latter including pulling force transmitting means effective to transmit pulling force'to the prop device from said main beam unit.

20. In mining apparatus, a cutting machine movable along a mine wall and having a cutting boom adapted to form a longitudinal overcut in said wall adjacent the mine. roof and with the bottom surface of the undercut sloping inwardly and upwardly toward said roof, a support railmounted on and connected with said cutting machine, a roof beam comprising elongated substantially lon u in l y g e ma n nd a xi ar beam having their adjacent ends connected with each other for 2O relative sliding movement therebetween, prop means conr nected'with and supporting the rear end of said main beam unit and being adapted to move the, same into engagement with said roof, said main beam-'unitrextending' forwardlyrfrom' said prop means'and over said support rail transversely thereof and being supported'at its for ward end and in a position adjacent said roof. by'said support rail, said auxiliary beam unit being extensible relative to said main beam unit for engagement of said auxiliary beam unit in said overcut, actuating means mounted on said roof beam. and .comprising relatively movable parts having operative connection respectively with said main beam unit and said auxiliary beam unit for extendingthe latter, and'bearing means on said auxiliary beam unit adjacent the forward end thereof and being slidable on said sloping bottom surface for wedging said beam upwardly toward said roof. 7 V

21. In mining apparatus, a plurality of roof beams having their forward ends supported by a longitudinal overcut formed in a mine wall adjacent the mine roof, a cutting machine movable along said wall beneath said beams and having driven devices for the removal from said wall of a work section extending beneath and beyond said overcut, a cutter of the boom type projecting from said machine and operable thereby for forming a second longitudinal overcut in said wall in advance of and in substantial alignment with the first-mentioned overcut as a new support for said forward ends when said beams are advanced to a new position, and a rail mounted on and connected with said cutting machine and forming a support movable with said cuttingmachine and engaging certain of said beams from .the underside thereof for supporting the forward ends of said certain beams when the first-mentioned overcut is destroyed by the removal of said 'work section.

22. In mining apparatus, a plurality of roof beams having their forward ends supported by a longitudinal overcut formed in a mine wall adjacent the mine roof, a cutting machine movable along said wall beneath said beams and having driven devices for the removal from said wall of a work'section extending beneath and beyond said overcut,'a cutter of the boom type projecting from 7 said machine and operable thereby for forming a second longitudinal overcut in said wall in advance of and in substantial alignment with the first-mentioned overcut as a new Support for said forward ends when said beams are advanced to a new position, a rail mounted on and of said beams, and means mounting said boom type cutter on said cutting machine for movement to and from said operating position. 7 a

23. In mining apparatus, a mineroof support beam having its forward end adapted to be supported on a mine wall by engagement in opening means extending into said wall adjacent the mine roof, said beam comprising elongated substantially longitudinally aligned main and auxiliary beam units having their adjacent end portions connected with each other for relative longitudinal V sliding movement therebetween, the auxiliary beam unit being extensible relative to said main beam unit by said sliding movement for engagement of said auxiliary be'arn unitin said opening means, a cutting machine movable along said wall and having a cutting boom extending in forwardly and upwardly inclined relation and adapted to form a longitudinal'overcut which extends into said a wall at a point below said opening means and slopes forwardly and upwardly substantially to, the plane of the mine roof, said mine wall including a generally triangular wall portion'remaining between said overcut and the plane of the mine roof, actuating means comprising relatively movable parts connected respectively with said main and auxiliary beam units and operable to advance said auxiliary beam unit in said opening means, cutter means on'the forward end of said auxiliary beam unit and adapted to separate said triangular wall portion from the mine roof during the advance movement of said auxiliary beam unit, and means on said cutting machine adapted to support said beam while said triangular wall portion is being separated from the mine roof.

24. In mining apparatus, a mine roof support beam having its forward end adapted to be supported on a mine wall by engagement in opening means extending into said wall adjacent the mine roof, said beam comprising elongated substantially longitudinally aligned main and auxiliary beam units having their adjacent end portions connected with each other for relative longitudinal sliding movement therebetween, the auxiliary beam unit being extensible relative to said main beam unit by said sliding 'movement for engagement of said auxiliary beam unit in said opening means, a cutting machine movable along said wall and having a cutting boom extending in forwardly and upwardly inclined relation and adapted to form a longitudinal overcut which extends into said wall at a point below said opening means and slopes forwardly and upwardly substantially to the plane of the mine roof, said mine wall including a generally triangular wall portion remaining between said overcut and the plane of the mine roof, a second cutting boom extending substantially horizontally from said cutting machine adjacent the plane of the mine roof and adapted to separate said triangular wall portion from the mine roof for deepening said opening means and merging the same with said overcut, actuating means comprising relatively movable parts connected respectively with said main and auxiliary beam units and operable to advance said auxiliary beam unit in said opening means, and means on said cutting machine adapted to support said beam while said triangular wall portion is being separated from the mine roof.

25. In mining apparatus, a mine roof support beam adapted to be supported on a mine wall by endwise engagement in a longitudinal overcut extending into said wall adjacent the mine roof, said beam comprising elongated substantially longitudinally aligned telescoping beam units one of which is extensible and retractible by reciprocating movement relative to the other and has its forward end engageable in said overcut, actuating means operably connected with said one beam unit and operable to produce said reciprocating movement, and cutter means connected with the forward end of said one beam unit and actuated by said reciprocating movement for deepening said overcut in said mine wall, said cutter means being elongated laterally in the longitudinal direction of said overcut.

26. In mining apparatus the combination of, roof support beams forming a protective canopy over a work area, a structure movable along a mine wall and having a cutting boom operable to form an overcut in said wall, a rail movable with said structure to a position beneath certain of said beams and forming a support therefor, said beams each comprising elongated substantially aligned main and auxiliary beam units having their adjacent ends connected with each other for relative longitudinal movement therebetween, said auxiliary beam units being extensible by said relative longitudinal movement for engagement of the forward ends of said auxiliary beam units in said overcut, actuating means comprising relatively movable parts connected respectively with said main and auxiliary beam units for producing said relative longitudinal movement, and power mechanism connecting said rail with said structure and operable to impart lifting and lowering movements to the rail, said lifting and lowering movements of said rail being effective to guide said auxiliary beam units of said certain beams into said overcut.

27. In mining apparatus the combination of, roof support beams forming a protective canopy over a work area, a structure movable along a mine wall, a cutting boom operable to form an overcut in said wall substantially in the plane of said beams for receiving the forward ends of said beams, mechanism mounting said cutting boom on said structure for operation therefrom including an elevator support movable to lift said cutting boom to an operative position substantially in the plane of said beams and to lower said cutting boom to an inoperative position for passage beneath said beams, a rail movable with said structure to a position beneath certain of said beams and forming a support therefor, said beams each comprising elongated substantially aligned main and auxiliary beam units having their adjacent ends connected with each other for relative longitudinal movement therebetween, said auxiliary beam units being extensible by said relative longitudinal movement for engagement of the forward ends of said auxiliary beam units in said overcut, actuating means comprising relatively movable l parts connected respectively with said main and auxiliary beam units for producing said relative longitudinal movement, and hydraulic cylinder means connecting said rail with said structure and operable to impart lifting and lowering movements to the rail, said lifting and lowering movements of said rail being effective to guide said auxiliary beam units of said certain beams into said overcut.

28. In a method of mining, the steps of forming a first longitudinal overcut in an elongated mine wall adjacent the mine roof such that the overcut extends into the mine Wall from the initial face thereof over a work section of the wall, advancing roof support beams and engaging their forward ends in said first overcut, removing said work section including said first overcut so as to leave a relatively advanced new face on said mine wall, forming a second such longitudinal overcut extending into the mine Wall from said new face, and again advancing said roof support beams and engaging their forward ends in said second overcut substantially at the rate of formation of the latter.

29. The mining method defined in claim 28 which includes the step of forming said second longitudinal overcut during the same work operation by which said work section is removed from the mine wall.

30. In a method of mining, the steps of forming a first longitudinal overcut in an elongated mine wall adjacent the mine roof such that the overcut extends into the mine wall from the initial face thereof over a work section of the wall with the bottom of said first overcut sloping upwardly toward said roof, advancing roof support beams and engaging their forward ends in said first overcut in sliding engagement with the sloping bottom thereof for wedging the beams upwardly against said mine roof, removing said work section including said first overcut so as to leave a relatively advanced new face on said mine wall, forming a second such slopingbottom longitudinal overcut extending into the mine wall from said new face, and again advancing said roof support beams and slidingly engaging their forward ends on the sloping bottom of said second overcut.

31. In a mining method, the steps of forming a first longitudinal overcut in an elongated mine wall adjacent the mine roof such that the overcut extends into the mine wall from the initial face thereof over a work section of the wall, advancing roof support beams and engaging their forward ends in said first overcut, removing said work section including said first overcut by progressive travel of a work area along the mine wall so as to leave a relatively advanced new face on said mine wall, mechanically supporting the forward ends of those of said roof support beams which are immediately opposite said work area, forming a second such longitudinal overcut extending into the mine wall from said new face, 

